<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style> 
    .parent{
      display: table;
      width: 100%;
      table-layout: fixed;
    }
    .left, .right {
      display: table-cell;
    }
    .left {
      background: #666;
      width: 100px;
      border-right: 20px solid transparent;
      background-clip: padding-box;
    }
    .right{
      background:#999;
    }
  </style>
</head>
<body>
  <div class="parent">
    <div class="left">
      <p>left</p>
    </div>
    <div class="right">
      <p>right</p>
      <p>right</p>
      <p>right</p>
      <p>right</p>
      <p>right</p>
      <p>right</p>
    </div>
  </div>
</body>
</html>  